A study of VitalView for behavioural and physiological monitoring in laboratory rats

We describe the use of a commercially available telemetry and data acquisition system to record heart rate, body temperature and activity of freely behaving rats with transmitters that operate without batteries (transponders). The system uses PDT 4000HR E-Mitters (Mini Mitter, OR, USA) to acquire animal temperature, heart rate and motor activity data. E-Mitters obtain power from a radiofrequency field produced by an ER-4000 energizer/receiver so that transponders can collect data on heart rate, body temperature and gross motor activity. ER-4000 energizers/receivers are designed to be placed below the animals' cage. Data output from receivers is managed by a Windows PC-based data acquisition system, VitalView. In this study, we report that a good correlation exists between VitalView and Powerlab for the determination of heart rate and between intra-abdominal (telemetric) and colonic body temperature (rectal digital thermometer) in rats. Assessment of this system by using agents that have well-documented effects on heart rate, body temperature and locomotor activity have also been determined. An additional feature of VitalView is the incorporation of behavioural inputs (feeding monitors to monitor duration and frequency of feeding and a lickometer to monitor drinking bouts) into the data acquisition system designed primarily to acquire data from the implanted transponders. Circadian rhythms for all parameters were established in rats with E-Mitters implanted. VitalView may be used for the determination of multiple parameters in freely behaving animals using transponders, which operate without batteries. This capability is unique in its field and represents a recent advance in biotelemetric monitoring of laboratory animals.     

Infant Rodent Ultrasounds – A Gate to the Understanding of Sound Communication

Components of the communication system between infant and adult rodents based on ultrasonic vocalizations (USVs) of infants are analyzed. USVs are most often emitted from a pup lost outside the nest in response to changes of: (i) body temperature, (ii) contact with adults/littermates, (iii) handling, and (iv) smell. These changes modulate the state of arousal and the emotional/motivational states and, as a result, USVs are produced. Acoustic properties of USVs seem to reflect the degrees of changes in arousal and emotion/motivation. Adult rodents are aroused by perceiving the USVs, locate the sender and show a phonotaxic approach to the sender. Acoustic properties of USVs in the frequency and time domains are described based on which adult rodents discriminate the USVs from other ultrasounds and take the USVs or adequate models of them as preferred goals of their phonotaxic approach. The preferred approach to adequate USVs is modulated by emotions/motivations, the sex of the receiver, hormonal states, experience with pups and neurotransmitter systems of the brain. The phonotaxis can be understood as the appetitive component of a pup-caring instinct. The consummatory act of the instinct is the retrieval of the lost pup. This retrieval is independent of USV presence, but it closes the communication loop activated by the emission of USVs. Communication with USVs can be used as a tool to investigate genetic and brain mechanisms of behavioral control.     

The effects of triiodothyronine (T3) on heart rate,temperature and ECG measured with telemetry in freely moving mice

We have set up a telemetry system and recorded heart rate, electrocardiogram (ECG), body temperature and the locomotor activity in awake freely moving mice. The telemetry system (DATA Sciences, St Paul, MN, USA) comprises a transmitter implanted in the peritoneal cavity and a receiver (RA1010) placed underneath the home cage. The signal from the transmitter includes the electrical activity of the heart and the body temperature. The results show that four days after the surgical procedure the mice have recovered and regained a clear circadian rhythm. The heart rate varied under baseline conditions between 432 and 618 beats min^?1 and the body temperature between 35.1 and 37.7 °C (based on 60 min mean values). A clear time correlation between heart rate, body temperature and locomotor activity was found. As an evaluation of the method we injected T₃ s.c. during a period of 4 days. Further, we were interested in whether it was possible to measure an integrated physiological response to T₃ and further investigate the time course for the effect. After one day of treatment with triiodothyronine there was a significant increase in body temperature and locomotor activity. The increase in heart rate was seen after 2 days. The ECG recording revealed a significantly shortened QT_end- and QRS-time. No significant difference in the PQ-time was found. This method may be of great importance in studies of genetically manipulated mice.     

Tunnel diode FM transmitter for medical research and laboratory telemetering

The design of a miniaturized FM radio transmitter using a tunnel diode as the main active element to broadcast information regarding body activity such as muscle and heart potentials to a remote receiver and recorder is reported. This FM transmitter has extremely high sensitivity. A maximum value of 500 kc/mV is obtained. The equivalent input noise of the complete transmitter and receiver system is 0.5 μV, at a signal to noise ratio of 20 dB. The dynamic range is 2×10³ (1μV to 2mV). The weight is 0.1 oz. with battery, and 0.04 oz. without battery. Results from field tests of the transmitter are also reported. Tests show that it is capable of transmitting body signals of 10 μV amplitude or stronger over a distance of 10–50 ft, with high fidelity and low noise. The interference from the A.C. power lines as well as other environmental noise, is greatly reduced. A two-wire input system may be used instead of the three-wire differential system. A frequency drift of 2 Mc/s between room temperature and body temperature was observed. The source of the temperature drift was discussed and compensating methods suggested. The feasibility of powering this transmitter by radio waves, light, heat, and mechanical motion is also discussed briefly.     

Effects of cryopreservation on human lymphocyte functions: comparison of programmed freezing method by a direct control system with a mechanical freezing method

The effects of cryopreservation with a new-type programmed freezer (TNP-82) were examined on natural killer (NK) activity and cell recovery of lymphocytes. This instrument is controlled by a sensor which directly detects the temperature in the samples, enabling easy setting of the temperature curve. Comparing results obtained by the new method to those from a less sophisticated mechanical method, cell recovery after cryopreservation was improved (95.3%) in the new compared to the older (about 80%) method. Furthermore, NK activity, percentage of Leu7+ cells and other lymphocyte functions were unaltered.     

Coevolution of telomerase activity and body mass in mammals: from mice to beavers

Telomerase is repressed in the majority of human somatic tissues. As a result human somatic cells undergo replicative senescence, which plays an important role in suppressing tumorigenesis, and at the same time contributes to the process of aging. Repression of somatic telomerase activity is not a universal phenomenon among mammals. Mice, for example, express telomerase in somatic tissues, and mouse cells are immortal when cultured at physiological oxygen concentration. What is the status of telomerase in other animals, beyond human and laboratory mouse, and why do some species evolve repression of telomerase activity while others do not? Here we discuss the data on telomere biology in various mammalian species, and a recent study of telomerase activity in a large collection of wild rodent species, which showed that telomerase activity coevolves with body mass, but not lifespan. Large rodents repress telomerase activity, while small rodents maintain high levels of telomerase activity in somatic cells. We discuss a model that large body mass presents an increased cancer risk, which drives the evolution of telomerase suppression and replicative senescence.     

Effect of social defeat in a territorial bird (Parus major) selected for different coping styles.

We addressed the questions (i) whether a social defeat triggers similar autonomic and behavioral responses in birds as is known from mammals and (ii) whether individuals that differ in coping style differ in their reaction to a social defeat. Adult captive male great tits (Parus major) from either of two different selection lines for coping style were used to test the effect of social defeat by an aggressive resident male conspecific on subsequent social and nonsocial behaviour, body temperature, breath rate and body mass. These parameters were measured 1 day before (baseline), immediately after and at Days 1 to 3 and 6 after the social interaction took place (Day 0). Social defeat decreased social exploration and increased body temperature substantially for at least 1 day in all birds. Breath rate and body mass were not affected. Birds belonging to the more aggressive and bolder line showed impairment in activity immediately after the social defeat. This is to our knowledge the first report showing that psychosocial stress in birds can have a similar impact as in rodents, but with a shorter recovery time. This might be due to species-specific differences in sensitivity to social stress, or to differences in the way social stress was induced.     

Effect of skin temperature on the cholinergic sensitivity of the human eccrine sweat gland

Although sweat gland activity is directly controlled by the central nervous system, which detects changes in core body temperature, sweat glands can also be influenced by local cutaneous thermal conditions. OBJECTIVE: The present study sought to determine the effect of local skin temperature on pilocarpine-induced sweating within a range of typical skin temperatures. METHODS: Thirteen subjects (30 +/- 6 years; 172 +/- 11 cm; 72.8 +/- 11.0 kg) had forearm sweat rates measured at rest following pilocarpine iontophoresis at each of three skin temperatures in randomized order: warm (T(warm) = 37.1 +/- 0.9 degrees C), control (T(con) = 32.3 +/- 1.4 degrees C), and cool (T(cool) = 26.6 +/- 1.3 degrees C). T(skin) was raised and lowered with an electric heating pad and gel ice pack, respectively. Forearm T(skin) was measured with a skin temperature probe. Pilocarpine iontophoresis was used on an approximately 7 cm(2) area of the anterior forearm to stimulate localized sweating. Following stimulation, sweat was collected from the area for 15 min with a Macroduct Sweat Collection System. RESULTS: There was a higher sweat rate at T(warm) (p = 0.001) and T(con) (p = 0.006) compared to that at T(cool). However, there was no difference between the sweat rate at T(warm) and that at T(con) (p = 0.127). CONCLUSION: These results indicated that skin temperatures below approximately 32 degrees C affect local sweat production primarily by altering glandular sensitivity to the neurotransmitter, whereas skin temperatures above approximately 32 degrees C predominantly affect neurotransmitter release. Furthermore, sweat glands display maximal or near maximal cholinergic sensitivity at resting skin temperature in a thermoneutral environment.     

Two strategies for coping with food shortage in desert golden spiny mice

Desert rodents face periods of food shortage and use different strategies for coping with it, including changes in activity level. Golden spiny mice (Acomys russatus) inhabit rock crevasses and do not dig burrows nor store food. When kept under 50% food restriction most, but not all, golden spiny mice defend their body mass by physiological means. We tested the hypothesis that these rodents use two different behavioral strategies, i.e., increasing activity level and searching for food or decreasing activity level and conserving energy to cope with food shortage. Twelve golden spiny mice were fed ad libitum for 14 days, followed by 40 days of 50% food restriction, and 14 days of refeeding. Body mass, food consumption and general activity were monitored. Seven mice significantly reduced activity level, concentrating their activity around feeding time, lowering energy expenditure and thus keeping their body mass constant ("resistant"), while five ("non-resistant") significantly increased activity level (possibly searching for food) and thus energy expenditure, thereby losing mass rapidly (more than 25% of body mass). The non-resistant golden spiny mice were active throughout many hours of the day, with high variability both between and among individuals. The use of two strategies to cope with food shortage as found in the golden spiny mice may be of evolutionary advantage, since it allows a more flexible reaction to food restriction at the population level.     

Quantitative Analysis of the Maturation of the Main and Accessory Olfactory Systems in Monotremes and Metatherians in Comparison to Rodents and Humans

We have used an unbiased statistical approach to compare the pace of development in the main and accessory olfactory systems in monotremes and metatherians with that in rodents and humans. We hypothesized that if metatherians and monotremes, which are born at small body size, use olfaction to locate the pouch and/or teat/milk field, then olfactory structures should reach structural maturity in metatherians and monotremes at a smaller size than eutherians like humans and rodents. The achievement of key structural milestones in the development of the main and accessory olfactory systems (11 and 7 milestones, respectively) was scored for 354 specimens and compared against a measure of general somatic growth (body length). We used a statistical approach adapted from Kaplan‐Meier analysis to determine median body length at which structural milestones were achieved, and to test the differences for statistical significance (Braslow statistic). The laboratory mouse achieved most main olfactory milestones at a smaller body size than all the metatherians and the monotremes, although the dasyurids (which are born at only 5.0 mm) and mouse achieved accessory olfactory milestones at similar body length. All other metatherians and monotremes reached olfactory milestones at body lengths similar to or larger than the laboratory rat. We therefore reject the hypothesis that metatherians and monotremes as a group exhibit advanced development of the olfactory pathways relative to body size. The findings suggest that, if olfaction is used by metatherians and monotremes at birth, it is achieved with only a rudimentary system without structurally mature central components. Anat Rec, 301:1258–1275, 2018. © 2018 Wiley Periodicals, Inc.     

The circadian body temperature rhythm of Djungarian Hamsters (Phodopus sungorus) revealing different circadian phenotypes

Djungarian hamsters (Phodopus sungorus) of our breeding stock show three rhythmic phenotypes: wild type (WT) animals which start their activity shortly after "lights-off" and are active until "lights-on"; delayed activity onset (DAO) hamsters whose activity onset is delayed after "lights-off" but activity offset coincides with "lights-on"; and arrhythmic hamsters (AR) that are episodically active throughout the 24-h day. The main aim of the present study was to investigate whether the observed phenotypic differences are caused by an altered output from the suprachiasmatic nuclei (SCN). As a marker of the circadian clock, the body temperature rhythm purified from masking effects due to motor activity was used. Hamsters were kept singly under standardized laboratory conditions (L:D=14:10h, T: 22°C±2°C, food and water ad libitum). Body temperature and motor activity were monitored by means of implanted G2-E-Mitters and the VitalView(?) System (MiniMitter). Each phenotype showed distinctive rhythms of overt activity and body temperature, these two rhythms being very similar for each phenotype. Correcting body temperatures for the effects of activity produced purified temperature rhythms which retained profiles that were distinctive for the phenotype. These results show that the body temperature rhythm is not simply a consequence of the activity pattern but is caused by the endogenous circadian system. The purification method also allowed estimation of thermoregulatory efficiency using the gradients as a measure for the sensitivity of body temperature to activity changes. In WT and DAO hamsters, the gradients were low during activity period and showed two peaks. The first one occurred after "lights-on", the second one preceded the activity onset. In AR hamsters, the gradients did not reveal circadian changes. The results provide good evidence that the different phenotypes result from differences in the circadian clock. In AR hamsters, the SCN do not produce an obvious circadian signal. With regard to DAO hamsters, it remains to be investigated whether the clockwork itself or the afferent entraining pathways are abnormal in comparison with the WT hamsters.     

Present understanding of the development of Mallory's body

Mallory's body filament assembly includes polypeptides of the cytokeratin class of intermediate filaments and also higher molecular weight polypeptides normally found only in the cytokeratins of mature keratinocytes of the epidermis. These additional polypeptides may alter both the morphologic characteristics and increase the resistance to dissolution of the filaments by Ca++-activated protease activity. Thus, it is likely that the kinetics of Mallory's body filament assembly and dissolution favor growth of the filaments. In rodents fed certain carcinogens, Mallory's body formation has been accompanied by the induction of the oncofetoenzyme gamma-glutamyl transpeptidase (GGT), suggesting that Mallory's body formation, like GGT induction, is a phenotypic change related to the process of neoplastic transformation in rodents.     

Orexin-a regulates body temperature in coordination with control of arousal state

Orexin-a regulates body temperature in coordination with control of arousal state     

Depth profiling of photothermal compound concentrations using phase sensitive optical coherence tomography

A model that describes the concentration of photothermal (light-to-heat converters) compounds as a function of depth in a turbid medium is developed. The system consists of a pump laser (808 nm modulated at 400 Hz), which heats a photothermal compound, and a phase sensitive spectral domain optical coherence tomography system, which detects the changes in the optical path length of the sample induced by the temperature increase. The model is theoretically derived and the coefficients are empirically determined using solid homogeneous gel phantoms. The model is validated by reconstructing the concentration of a photothermal compound in thick single and double layer solid phantoms.     

Role of intrahypothalamic insulin in circadian patterns of food intake, activity, and body temperature.

These experiments examined the extent to which chronic intrahypothalamic (IH) insulin infusions that alter circadian patterns of food intake (FI) affect the regulation of other diurnally varying behavior in the rat. One-week IH insulin infusion (1.5 microU/hr) significantly decreases rats' night FI and increases day FI but does not alter the diurnal pattern of activity. Mean daily core temperature increased slightly but significantly during insulin infusion, the daily peak of the body temperature rhythm did not shift significantly, and the daily range of body temperature increased. IH insulin infusion in rats living in constant light and thus without circadian rhythm of FI led to significant decreases in FI and body weight. These data support the conclusion that IH insulin infusion alters food intake and body weight through a specific effect on a neural system that regulates food intake and body weight, and not by altering circadian rhythms.     

Effects of fasting on the circadian body temperature rhythm of Japanese quail

The effect of food deprivation on the body temperature and activity rhythms of quail was assessed in birds exposed to both light-dark (LD) cycles and to continuous darkness (DD). Quail normally exhibit a daily rhythm of body temperature in LD that will persist in DD (that is, the rhythm is circadian). In LD, 3 days' food deprivation caused the body temperature to drop below its normal nighttime levels, whereas daytime body temperature was unaffected. In DD, food deprivation caused the body temperature to drop below normal at all phases of the circadian rhythm of body temperature. Accordingly, the lack of hypothermia during the light phase of the LD cycle following food deprivation must represent a direct exogenous or "masking" effect of light, and is not an endogenous property of the circadian system. Blind birds exposed to LD 12:12 exhibited an entrained body temperature rhythm, and food deprivation caused a drop in body temperature below normal levels during both the light and dark phases of the LD cycle. Accordingly, the masking effects of light observed in normal birds on LD cycles is mediated via retinal photoreceptors and not via extraretinal photoreceptors. Measurements of activity levels before and during fasting indicate that fasting-induced hypothermia cannot be explained simply as a consequence of decreases in activity levels. Food deprivation was also observed to cause significant phase shifts in the endogenous rhythm of body temperature.     

An underwater temperature telememetry system

An underwater telemetry system has been developed which is capable of monitoring temperatures of three points on a submerged diver. Temperature leads from the diver rum to an ultrasonic transmitter attached to the diver's SCUBA tanks. Telementry signals from the transmitter propagate through the water to a receiver located at a convenient monitoring point. High accuracy over the system temperature range of ?4·0 to +40·0°C is achieved by using an octal number system for encoding the data. The data received is recorded on a standard strip chart recorder in the digital form at rate of one reading per second. Conversion of the data is accomplished by use of tables which relate the octal numbers to temperature. Accuracy of the system is limited primarily by thermistor accuracy which is within±0·2°C. System resolution is ±0·03°C at normal body temperature.     

Behavior and body temperature in rats following chronic foot shock or psychological stress exposure

In an attempt to examine stress-induced behavioral disorders, including circadian rhythm disturbances, we measured motor activity, feeding, drinking, and body temperature over a 14-day period following a long-term stress exposure in rats. Male Wistar rats were exposed to foot shock (physical) or non-foot shock stress (psychological) induced by the communication box for 1 h daily over 12 weeks. Two to three months after the termination of the stress sessions, motor activity, food intake, water intake, and body temperature were measured by means of an automatic behavioral measurement system under a 12:12-h light:dark cycle. Motor activity, feeding, and drinking patterns were not influenced by either of the previous stress exposures. Daily rhythm of body temperature was also unchanged in either stress group, however, a significant elevation in body temperature (by 0.20 degrees C, p<0.05) was observed only in non-foot-shocked rats. The present study suggests that only psychological stress induces an elevation of body temperature following the stress exposures; however, long-term stress exposures in the present experiment do not disturb behavioral activities and daily rhythms of behaviors.     

Reduced cold-induced thermogenesis in familial human obesity

Summary It is well known that cold and diet-induced thermogenesis, which is mediated in small rodents by the hypothalamic-noradrenergic fibersbrown adipose tissue axis, is impaired in genetically obese mice. To test whether these adaptive mechanisms are also impaired in obese humans, 12 young males who were otherwise healthy (6 lean and 6 obese) were examined. The obese subjects had an early-onset type of obesity with a strong family history of it as well. Deep body temperature was measured by using a deep body thermometer furnished with three thermocouples. They were respectively placed on the sternum, on the interscapular area immediately under the neck (HIS), and on the 4th intercostal space (LIS) in order to study core temperature as well as heat production where brown adipose tissue could also be present in adults. Both lean and obese subjects were kept in a thermoneutral environment (28° C) until they reached a steady-state body temperature and then rapidly transferred into a cold room (6–8° C) where they remained up to 60 min. Body temperature decreased in both groups, but the decrease was more marked in the obese individuals on the sternum (P<0.01), on HIS (P<0.05) and on LIS (P<0.05) when compared to lean individuals. In conclusion, cold-induced thermogenesis is impaired in familial early-onset human obesity and in genetically obese mice.Abbreviations BAT brown adipose tissue - BMI body mass index - HIS high interscapular area - LIS low interscapular area     

Sleep in the blind mole rat Spalax ehrenbergi

STUDY OBJECTIVES: The mole rat, Spalax ehrenbergi, is an interesting species for sleep because of its pronounced specialization to a fossorial life. These rodents spend most of their life-time underground, and are less exposed to many of the environmental stimuli and challenges that are common to non-fossorial rodents. A prominent adaptation is their blindness, which is due to an atrophy of the eyes. DESIGN: Continuous 24-h recordings of EEG, EMG and cortical temperature, and EEG spectral analysis were performed in six individuals caught in the wild and adapted to the laboratory for several months. SETTING: N/A. PATIENTS OR PARTICIPANTS: N/A. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Total sleep time (52% of recording time) and the amount of REM sleep (8% of recording time) in these subterranean rodents are in the range of values found in the laboratory rat, mouse and hamster recorded under similar conditions. In contrast to these species, the polyphasic sleep-wakefulness distribution in mole rats was more distinct. A predominance of sleep in the dark period was only minor and not present in all individuals, which resembles sleep in the guinea pig. As in all other mammals investigated, the daily time course of EEG slow-wave activity (SWA) in nonREM sleep closely followed the polyphasic sleep-wake pattern and the light-dark preference. The transitions from non REM sleep to REM sleep were characterized, as in other rodents, by a gradual increase in EEG activity in the theta and sigma frequency bands before the transition. However, the power surge in these frequencies massively exceeded that found in other rodents. This feature may be related to adaptations of the brain to the requirements of the subterranean habitat. CONCLUSIONS: It is remarkable that large ecological differences between species within the same order have relatively small effects on many sleep features. The time course of SWA confirmed its predictability on the basis of the previous sleep-wake history.